module-based literate programming

static/js/components/literate-programming/worker.js

@@ -1,26 +1,50 @@
-console = {
+let outputIndex = 0;
+
+let debugLog = console.log;
+
+globalThis.console = {
     log(...message) {
         postMessage({
             kind: "output",
             output: {
                 kind: "log",
                 message: [...message],
-            }
+            },
+            outputIndex,
         });
     }
 };
 
-addEventListener("message", event => {
+async function withTemporaryGlobalScope(callback) {
+    let state = {
+        oldValues: {},
+        set(key, value) {
+            this.oldValues[key] = globalThis[key];
+            globalThis[key] = value;
+        }
+    };
+    await callback(state);
+    for (let key in state.oldValues) {
+        globalThis[key] = state.oldValues[key];
+    }
+}
+
+addEventListener("message", async event => {
     let message = event.data;
     if (message.action == "eval") {
+        outputIndex = 0;
         try {
-            let func = new Function(message.input);
-            let result = func.apply({});
-            postMessage({
-                kind: "output",
-                output: {
-                    kind: "result",
-                    message: [result],
+            await withTemporaryGlobalScope(async scope => {
+                for (let command of message.input) {
+                    if (command.kind == "module") {
+                        let blobUrl = URL.createObjectURL(new Blob([command.source], { type: "text/javascript" }));
+                        let module = await import(blobUrl);
+                        for (let exportedKey in module) {
+                            scope.set(exportedKey, module[exportedKey]);
+                        }
+                    } else if (command.kind == "output") {
+                        ++outputIndex;
+                    }
                 }
             });
         } catch (error) {
@@ -29,7 +53,8 @@ addEventListener("message", event => {
                 output: {
                     kind: "error",
                     message: [error.toString()],
-                }
+                },
+                outputIndex,
             });
         }